Portland cement and process for making the same.



106. COMPOSITIONS,

COATING OR PLASTICJ W Z M72 %4 it W, /7

Examiner.

NT OF PORTLAND CEMENT AND PROCESS FOR MAKING THE SAME.

Specification of Letters Patent.

Patented Sept. 17, 1907.

Application filed February 28,1907. Serial No. 359,747.

To all whom it may concern:

Be it known that I, RICHARD KIDDER MEADE, a citizen of the UnitedStates, residing at Nazareth, in the county of Northampton and State ofPennsylvania,

5 have invented certain new and useful Improvements in Portland Cementand Processes of Making the Same, of which the following is aspecification.

This invention relates to an improved process of making Portland cement,and to the product resulting 10 therefrom, and has particular referenceto a process of making a high grade of Portland cement wherein there isemployed high nnqnesian limestone, which has not heretofore beensuccessfully utilized in cement manufacture. 1 5 In the manufacture ofPortland cement, as commonly practiced, a mixture of argillaceous andcalcarious substances in the 'proper proportions is ground to animpalpable powder, then burned to the point of incipient/"jvitrifaction, and the resulting greenish-black clinker reduced to animpalpable powder. It has been found by experience that the argillaceousmaterial, as silica, oxicl of iron and alumina, should bear to thecalcarious material, as lime a ratio of approximately 1 to 2.

A large proportion of the Portland cement manufac- 2 5 tured in theUnited States is made from an argillaceous limestone called cement rockfound in Warren county, New Jersey, and in Berks, Lehigh and Northamptoncounties, Pennsylvania. This rock contains usually from 65 to 75 percent. carbonate of limg, and

0 from 18 to per cent. argillaceous matter, principally silica, oxid ofiron and alumina. When the rock contalns less than 75 per cent. ofcarbonate of lime, it is necessary to add to the same a quantity oflimestone, preferably pure, sufficient to bring the total carbonate oflime content in the mixture up to approximately 75 per cent. There arein the vicinity of the cement rock deposits throughout the sectionsmentioned extensive deposits of limestone containing more than 4 percent. of magnesia, or what is termed in the art high magnesianlimestone, but in these sections there is very little limestone having alow content of magnesia. Now the high magnesian limestone cannot atpresent be used with the cement rock, because Portland cement made fromsuch limestone will have low tensile strength,

and will also expand and crack when used in concrete. It has thereforebeen found necessary in working the cement rock to bring limestone,practically free from or containing a low content of magnesia from somedistant point to the Portland cement mills, thereby greatly increasingthe cost of production. In fact in some of the mills in the sectionsabove mentioned it is necessary to addas much as one tonof limestone toevery two tons of the cement rock, and to bring this limestone from adistance of over one hundred miles.

It is obvious therefore, that if these mills could use the highmagnesian limestone deposits, which exist in the m ma; 1 m K immediateneighborhood of the cement rock deposits, it would enable themanufacturers to very greatly cheapen the cost of Portland cementmanufacture, as it would then be unnecessary to bring low magnesianlimestone from distant deposits to mix with the cement rock.

This invention consists in a process by which a high grade of cement,superior in strength to the best grades of Portland cement, can be madefrom high magnesian limestone, and particularly limestone containingfrom 5 to 20 per cent. of magnesia, in connection with cement rock.

My process in its preferred embodiment consists in mixing with cementrock sufficient high ma ne- 7 sian limestone to bring the l1me andmagnesia in the mixture up to the proper ratio to the silica, iron oxidand alumina, the preferred ratio of the calcarious material to theargillaceous material being approximately 2 to 1. The mixture is theirround to an impalpable powder, burned to the poinmient vitrifaction anda s percentage, preferably from one to ten per cent. by weight ofcalcium chlorid is added to the clinker and the mixturegroun o erequisite fineness. The proportion of calciu chlorid to the mixture willdepend upon the perc tage of magnesia in said mixture, satisfactoryresults being obtained by the addition of 2 per cent. of calcium chloridto a cement mixture containing eight per cent. of ma nesia. I Where thecement mixture contains a larger percentage of magnesia, aproportionally larger amount of the chlorid will be required.

In place of calcium chlorid I may employ other .-chlorids, preferablymetal chlorids, such for example as sodium or other alkaline phlorids,ma nesium or other chloride of metal bf tli dmagnesium group,

b rium or other al lgalige gagth chlorids' the various chlorids beingequivalents of the calcium chlorid mentioned, in the practice of myprocess.

The calcium or other chlorid employed may be added to the materials usedin the manufacture of cement before grindi g, or before burning, or itmay be added tdtli''cfifiker at any tlme dr gingplimggss of grinding, orit may be added to the cement before msed, or to the water or othermaterial mixed 00 with the cement; it being sufiicient that the chlorida be incorporated with the high magnesian lii nestone c nent' at"anytime prior to the crystallization or setting of the latter in use, andany such incorporation 1'5 (resided to be within the spirit of myinvention, and i the scope of the protection for which I have madeapplication.

G sum or laster of aris may be added to the 3 mfimmdrcmg the cement atany time either before or after grinding if found necessary in 211131;weg late the set. Thecalciumchlorid, or i its equivalent however servest liig purpgse, so that the Mara; 7M t /Vis 4 77",? WW) [/M-Zy) additionof gypsum or plaster of paris is in most cases wholly unnecessary.

In use, the calcium or other chlorid employed combines with thefree-magnesium oxid in the cement when the latter is mixed with water,and not only renders the latter innocuous, but also forms with it an'oxychlorid compound having itself great cementing to produce by suchuse a superior quality of cement.

Having thus described my invention 1 claim:

1. The herein described process cornprisin; heating a mixture ofargillaceous material and calcarious material containing more than 3 per'cent. of magnesia, and incorporating therewith a chlorid.

2. The herein described process comprising heating to' incipientvitrifaction a mixture of argillaceous material and magnesian limestonecontaining more than 3 per cent. of magnesia, and incorporatingtherewith a metal chlorid.

3. The herein described process comprising heating to incipientvitrifaction a mixture of argillaceous material and magnesian limestonecontaining more than 4 per cent. of magnesia, and incorporatingtherewith a chlorid in an amount proportioned to the quantity ofmagnesia in the said mixture.

4. The herein described process comprising heating to incipientvitrifaction a mixture of argillaceous material and magnesian limestonecontaining more than 4 per cent. of magnesia. and incorporating calciumchlorid therewith in an amount proportioned to the quantity of magnesiain the said mixture.

The herein described process comprising heating to incipientvitrifaction a mixture of argillaceous material and limestone containingfrom 5 to per cent. of magnesia, and incorporating therewith a chloridin an amount proportioned to the quantity of magnesia in the saidmixture.

In testimony whereof I afiix my signature in presence of two witnesses.

RICHARD KIDDER MEADE.

Witnesses 'ILLIAM P. GANO, LESTER C. HAWK.

